Traditionally, electric lawn mower construction has consisted of a single switch to activate the lawn mower. Accordingly, it was possible to activate the lawn mower with one hand. Examples of such a configuration may be seen in U.S. Pat. No. 3,500,620 to Duran et al. and U.S. Pat. No. 3,298,163 to Ottosen et al.
Lawn mowers then provided a remote control lever for operating the on/off switch with a motor for an electric mower to enable the operator to stand a distance from the housing when engaging the motor. An example of such a configuration is disclosed in U.S. Pat. No. 3,564,186 to Mittelstadt. Subsequently, handles or control bars were utilized which were spring-biased to an OFF position which required that both switches be placed to an ON position to start the electric motor as disclosed in U.S. Pat. No. 3,230,695 to West.
Eventually, the dual control switches were incorporated into a generally U-shaped, one-piece handle commonly referred to as a bail bar to provide improved operator control and minimize fatigue associated with holding onto two separate switches. Such a configuration is disclosed in U.S. Pat. No. 4,476,643 to Hilchey et al.
In 1984, in response to existing and proposed standards for lawn mowers, U.S. Pat. No. 4,466,308 to Kester et al. disclosed a control assembly for lawn mowers including a dead-man function requiring two distinct steps for starting of the lawn mower engine.
On Dec. 8, 1989, Underwriters Laboratory, Inc. published a revised standard for electric lawn mowers under UL 1447, 2nd Edition, Section 26, which required that:
the lawn mower be provided with a means that must be manually actuated before the blade or blades can be restarted such that the means may be either a control that is separate from the blade control or it may be incorporated into the blade control's double action device that requires two separate actions to restart the blade or blades.
Underwriters Laboratory 1447, 2nd Edition, Section 26 is incorporated herein by reference.
The present invention is directed to improving known activation switches for electric lawn mowers while adopting Underwriters Laboratories 1447, 2nd Edition, Section 26 requirements.